1. Field of the Invention
The present invention relates to an ophthalmic laser irradiation apparatus for irradiating a laser beam onto a patient's eye.
2. Description of Related Art
As an ophthalmic laser irradiation apparatus for irradiating a laser beam onto a patient's eye, for example, there is a corneal laser surgery apparatus which ablates a corneal tissue by irradiating an excimer laser beam and changes corneal curvature to correct a refractive error of the eye. In addition, as the ophthalmic laser irradiation apparatus, there is an apparatus provided with an alignment mechanism for aligning an irradiation position of the laser beam (hereinafter, also simply referred to as an “irradiation position”) with reference to a predetermined position of the eye, and further provided with a tracking mechanism for aligning (moving) the irradiation position even if the eye (an eyeball) moves during operation. Further, as an apparatus provided with those alignment mechanism and tracking mechanism, such an apparatus is proposed that determines the irradiation position with reference to a position (part) relating to a pupil (including an iris which forms the pupil) such as a pupil center position.
The pupil (iris), however, changes (dilates, contracts, and the like) depending on brightness. Further, due to the charge in the pupil (iris), also various positions (parts) such as the pupil center position change (deviate) Therefore, in a case where the irradiation position is determined with reference to the position (part) relating to the pupil (iris), if the pupil (iris) changes, the irradiation position is misaligned, and it causes an error in a post-operative correction result.